There is an ever increasing interest among consumers in food products which contain less total fat, saturated fat, cholesterol and calories. Such products are useful in controlling body weight and reducing the risk of heart and artery disease.
Traditional full-fat cheese products which contain butterfat generally contain from about 15% to about 35% fat, from about 50 mg to about 100 mg cholesterol per 100 g, and from about 300 to about 400 calories per 100 g. Because of this high fat and calorie content, there has long been a significant need for cheese analogs which have a substantially reduced fat and reduced calorie content and yet which provide the gustatory and physical properties of conventional butterfat-containing cheese analogs.
For many years, synthetic cheese analogs have been made wherein the butterfat traditionally present in full-fat cheese was replaced with an alternative, less expensive, animal or vegetable fat. In almost all cases, the synthetic cheeses are offered at lower cost, which was probably the most important single factor in the initial acceptance of synthetic dairy foods. Another beneficial aspect of synthetic cheese analogs is the fact that many such products can be produced with an extended shelf life. With the increased awareness of the dangers of cholesterol found in animal fats, synthetic cheese analogs wherein the butterfat is replaced with a vegetable fat have gained increased popularity. The term "animal fats" as used herein encompasses the fats derived from dairy, fish or meat sources.
Synthetic cheeses are made utilizing aged or non-aged low-fat cheese, vegetable-derived protein such as soy or soy isolate, or commercially available dry powdered protein derived from fresh, whole or skim milk, buttermilk or cream such as, for example, sodium or calcium caseinate. Synthetic cheese products using proteinaceous materials derived from vegetable sources are described in U.S. Pat. No. 4,684,533 to Kratochvil; U.S. Pat. No. 4,678,676 to Ishizuka, et al. and U.S. Pat. No. 3,806,606 to Seiden. Synthetic cheese products made from a commercially available dry powdered protein derived from fresh whole milk are described in the following patents: Canadian Pat. 952,761 to Roe; U.S. Pat. No. 3,941,891 to Kasik, et al.; U.S. Pat. No. 4,197,322 to Middleton and U.S. Pat. No. 4,397,926 to Galal, et al. Finally, conventional synthetic cheese utilizing skim milk cheese, a non-aged low-fat cheese, is described in U.S. Pat. No. 2,604,405 to Petersen, herein incorporated by reference.
U.S. Pat. No. 5,080,912 to Bodenstein, et al. describes a process for preparing a cheese product wherein a polyol fatty acid polyester is substituted for a portion of the milk fat usually present in cheese. In the method of the Bodenstein, et al. patent, a water and oil containing filled milk is prepared containing polyol fatty acid polyesters as a portion of the filled milk. After homogenization, a cheese milk is prepared by combining the filled milk with an aqueous composition containing at least 2 weight percent milk protein. A starter culture and/or a milk coagulant is added to the cheese milk and the cheese milk is permitted to coagulate. The coagulum is cut to provide curd particles and whey and the whey is separated from the curd as in conventional cheese making processes.
U.S. Pat. Nos. 5,061,503 and 5,061,504 to Kong-Chan, et al. are directed to simulated cheese products with reduced animal fat and calories. The cheese products of the Kong-Chan, et al. patents contain from about 5% to about 50% of protein obtained from aged low-fat cheese, non-aged low-fat cheese, aged full-fat cheese, non-aged full-fat cheese, dry-powdered protein derived from fresh whole milk, skim milk, buttermilk, vegetable protein and mixtures thereof. The cheese products also contain from about 4% to about 35% of a fatty substance. From about 30% to 100% of the fatty substance is a low calorie fatty material with the balance being animal fat or vegetable fat. The fatty material is selected from a low-calorie fatty material which is a polyester of a sugar or sugar alcohol, or a tailored triglyceride in which the esterifying acids are a mixture of long chain and medium chain triglycerides.
The manufacture of cheese or cheese base materials from milk through preparation of a retentate by removal of salts, lactose and water has been taught in various patents and literature references. For example, U.S. Pat. No. 3,988,481 to Coulter, et al., teaches the preparation of cheese from milk which has been delactosed and dewatered by a processing involving molecular sieving a standardized milk to substantially separate and remove lactose and water-soluble minerals from the milk to render the milk substantially sugar-free, and adding a curd-forming agent to produce curd. The resulting curd is subjected to conventional handling without substantial syneresis to produce a cheese, and molded to a desired form.
U.S. Pat. No. 3,899,596 to Stenne discloses a process for the production of cheese which comprises treating milk by ultrafiltration to obtain a product having at least some of the protein constituents of the milk, renneting the liquid product after inoculation with suitable ferments, and introducing a batch of the renneted liquid into a vertical chamber in which it is left to coagulate. The coagulum is cut into slabs which provide the end product cheese. U.S. Pat. No. 3,914,435 to Maubois, et al. teaches cheese made from heat-treated milk and without conventional draining of whey by a process which involves ultrafiltering of the milk to produce a concentrate having essentially the composition of cheese produced by conventional whey draining processes. The process enables the milk, after ultrafiltration, to be heat-treated without making the milk more difficult to coagulate with rennet, which difficulty normally occurs when milk is heated to high temperature.
U.S. Pat. No. 4,244,971 to Wargel, et al. teaches the manufacture of cheeses and process cheese, from ultrafiltered milk.
U.S. Pat. No. 4,401,679 to Rubin, et al. discloses a process for preparing cheese base by concentrating milk through ultrafiltration, combined with diafiltration and evaporation, wherein the retentate from the ultrafiltration is inoculated with an acid culture before evaporation, and after evaporation acidification proceeds to completion in packing.
Further, cheese base material has been taught by evaporating moisture from retentate under turbulent conditions to provide a lower moisture condition. Such a process is described in an article by Ernstrom, et al., "Cheese Base for Processing: A High-Yield Product from Whole Milk by Ultrafiltration", published in the Journal of Dairy Science, Volume 63, 228-234 (1980). The article teaches a process wherein whole milk of normal pH, or acidified to a pH of 5.7, is concentrated by ultrafiltration to about 40 percent of the original milk weight and diafiltered at constant volume until a desired ratio of lactose to buffer capacity is established. Then the retentate is further concentrated by ultrafiltration to 20 percent of the original milk weight. The retentate is then inoculated with cheese starter and incubated to completely ferment the residual lactose, pH control being achieved by controlling the level of lactose remaining after a diafiltration step in the process. The product is further concentrated in a swept-surface vacuum-pan evaporator or a continuous-flow Luwa evaporator. It is pointed out that the use of a batch evaporator is necessitated when the retentate, upon fermentation, curdles or coagulates, since such a product cannot be readily processed in any continuous-flow evaporator.
It is known to add salt during fermentation to prevent coagulation and this was understood many years ago. See, LeLait, November-December, 1974, No. 539-540. Further, it has been disclosed that salt in the retentate may facilitate evaporation as disclosed in an Australian patent application, which is the subject of a published application under the Pat. Cooperation Treaty WO82/01806, published Jun. 10, 1982.
The prior art teaches that the addition of rennet or other coagulating enzymes to high-solids milk systems causes rapid coagulation, a condition to be avoided during evaporation, of a retentate, since the evaporation is highly inefficient after coagulation occurs. On the other hand, the presence of coagulating enzymes is desired in hard or high-solids cheese to provide the conventional presence of para kappa casein.
In the conventional making of cheese with rennet, the macro peptides formed by rennet action are lost in the whey with consequent reduction in yield and loss of nutritious milk protein material. Accordingly, it would be desirable to enjoy the benefit of rennet action while avoiding whey removal with consequent loss of macro peptides.
Further, prior art methods for making cheese products at high-solids with evaporation, in which evaporation is effected with high turbulence or the cheese base material is recovered with substantial working after evaporation, has resulted in oiling-off or destabilization of higher-solids cheese and a body and texture unlike various cheeses. This destabilization is particularly noticeable at total solids in excess of about 60 to about 62 percent, e.g., a cheese such as cheddar cheese, but is also present at solids as low as 55 percent. Accordingly, cheese base materials heretofore produced by evaporating retentates to a total solids in excess of 60 percent have not provided the typical body and texture characteristics of high-solids cheeses.
Despite the many teachings of the prior art relating to the manufacture of cheese products and cheese-based materials from retentates derived from milk, there has been no prior art teaching of a process for producing higher-solids cheese wherein the milk fat is replaced with a non-digestible fatty material, such as polyol fatty acid polyester.
Accordingly, it is an object of the present invention to provide a cheese product which is stable and does not oil-off and is manufactured by processing a retentate with evaporation techniques and which contains a polyol fatty acid polyester as a substitute for at least a portion of the triglyceride fat normally present in cheese analogs.
It is another object of the present invention to provide a cheese analog from a retentate by means of evaporation techniques, the cheese being stable and capable of having typical body and texture characteristics associated with a natural cheese.
It is a further object of the present invention to provide a cheese analog with reduced levels of digestible fat which is suitable for use in the manufacture of processed cheese.